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IC MAGE FM02 is a user-defined flow model for PLAXIS that allows the simulation of mean effective stress-dependent anisotropic permeability., {"references":["Gawecka, K.A., Taborda, D.M.G., Potts, D.M., Cui, W., Zdravkovic, L., Haji Kasri, M.S. (2017) Numerical modelling of thermo-active piles in London Clay. Proceedings of the ICE: Geotechnical Engineering, 170(3): 201-219."]}

IC MAGE M04 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which combines a Mohr-Coulomb failure criterion with the IC.G3S isotropic small strain stiffness model and the nonlinear scaling factor proposed by Taborda & Zdravkovic (2012). It allows for the generation of hysteresis (and energy dissipation) by adopting a cyclic nonlinear elastic framework., {"references":["Darendeli, M. B. (2001) Development of a new family of normalized modulus reduction and material damping curves. PhD Thesis. University of Texas, Austin.","Korma, E. (2014) The Influence of Advanced Features of Cyclic Soil Response on Wave Propagation Problems. M.Sc. thesis. Imperial College London, London, UK.","Rollins, K. M., Evans, M. D., Daily, W. D., III & Diehl, N. B. (1998) Shear modulus and damping relationships for gravels. Journal of geotechnical and geoenvironmental engineering, 124 (5), 396-405. https://doi.org/10.1061/(ASCE)1090-0241(1998)124:5(396)","Taborda, D.M.G., Potts, D.M. and Zdravković, L. (2016). On the assessment of energy dissipated through hysteresis in finite element analysis. Computers and Geotechnics, 71, 180–194. https://doi.org/10.1016/j.compgeo.2015.09.001","Taborda, D.M.G and Zdravković, L. (2012). Application of a Hill-Climbing technique to the formulation of a new cyclic nonlinear elastic constitutive model. Computers and Geotechnics, 43, 80-91. https://doi.org/10.1016/j.compgeo.2012.02.001","Taborda, D.M.G., Kontoe, S. & Tsiampousi, A. (2021, June 23). IC MAGE UMIP - universal model interface for PLAXIS (Version 2.0). Zenodo. http://doi.org/10.5281/zenodo.5018865","Vucetic, M. & Dobry, R. (1991) Effect of soil plasticity on cyclic response. Journal of Geotechnical Engineering, ASCE, 117 (1), 89-107. https://doi.org/10.1061/(ASCE)0733-9410(1991)117:1(89)"]}

The structural assessment of segmental grey cast iron (GCI) tunnel linings to nearby construction is challenging due to the presence of the joints affecting the stiffness of the tunnel lining. This paper presents an extensive investigation, using 3D finite element (FE) analyses, into the bending moment-rotation (M-θ) behaviour of two GCI tunnel joint geometries. These two geometries correspond to standard running and station tunnels of the London Underground network. The contribution of this study is two-fold. i) The novel characterisation of the M-θ response enables the development of new models for simulating the mechanical response of GCI tunnel joints with structural elements which can be used in simplified, 2D geotechnical analysis for tunnel safety assessments. ii) The analyses provide insight into the behaviour of GCI tunnel linings that would be difficult to achieve through experimental and field observations alone. More specifically, the analyses show that when the bolts are removed from the joints the possibility of tensile failure can be disregarded; that the initial bolt preload influences the rotational stiffness only after some rotation has taken place and does not alter the bending moment of opening; and that the out-of-plane displacement restraint has little influence on the joint response.

IC MAGE FM01 is a user-defined flow model for PLAXIS that allows the simulation of spatially-varying anisotropic permeability., {"references":["Avgerinos, V. (2014) Numerical investigation of tunnelling beneath existing tunnels. PhD Thesis, Imperial College London, UK.","Hight, D.W., Gasparre, A., Nishimura, S., Minh, N.A., Jardine, R.J., Coop, M.R. (2007) Characteristics of the London Clay from the terminal 5 site at Heathrow airport. Géotechnique, Vol.57, No.1, pp.: 3–18."]}

IC MAGE M02 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which combines the state-parameter framework by Been & Jefferies (1985) with a Mohr-Coulomb failure criterion. The elastic response is given by the isotropic small strain stiffness model IC.G3S by Taborda et al. (2016). A reversal detection algorithm within a cyclic nonlinear elastic framework allows for the generation of hysteresis (and energy dissipation)., {"references":["Been, K. and Jefferies, M.G. (1985) A state parameter for sands. Geotechnique, 35(2), 99-112. https://doi.org/10.1680/geot.1985.35.2.99","Taborda, D.M.G., Potts, D.M. and Zdravković, L. (2016). On the assessment of energy dissipated through hysteresis in finite element analysis. Computers and Geotechnics, 71, 180–194. https://doi.org/10.1016/j.compgeo.2015.09.001","Taborda, D.M.G., Potts, D.M., Zdravković, L. and Pedro, A.M.G. (2018) Incorporating the state parameter into a simple constitutive model for sand. Numerical Methods in Geotechnical Engineering IX. https://doi.org/10.1201/9780429446931","Taborda, D.M.G and Zdravković, L. (2012). Application of a Hill-Climbing technique to the formulation of a new cyclic nonlinear elastic constitutive model. Computers and Geotechnics, 43, 80-91. https://doi.org/10.1016/j.compgeo.2012.02.001","Taborda, David M G, Kontoe, Stavroula, & Tsiampousi, Aikaterini. (2021, June 23). IC MAGE UMIP - universal model interface for PLAXIS (Version 2.0). Zenodo. http://doi.org/10.5281/zenodo.5018865"]}

IC MAGE M03 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which combines a strain-hardening/softening Mohr-Coulomb failure criterion based on the deviatoric plastic strain with the IC.G3S transversely isotropic small strain stiffness model. It allows for the generation of hysteresis (and energy dissipation) by adopting a cyclic nonlinear elastic framework., {"references":["Taborda, David M G, Kontoe, Stavroula, & Tsiampousi, Aikaterini. (2021, June 23). IC MAGE UMIP - universal model interface for PLAXIS (Version 2.0). Zenodo. http://doi.org/10.5281/zenodo.5018865"]}

IC MAGE M01 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which combines a strain-hardening/softening Mohr-Coulomb failure criterion based on the deviatoric plastic strain with the IC.G3S (Taborda et al., 2016) isotropic small strain stiffness model. It allows for the generation of hysteresis (and energy dissipation) by adopting a cyclic nonlinear elastic framework. Safety analyses are also allowed using this model.

IC MAGE M09 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which combines the state-parameter framework by Been & Jefferies (1985) with a Mohr-Coulomb failure criterion. The elastic response is given by the isotropic small strain stiffness model IC.G3S by Taborda et al. (2016). A reversal detection algorithm within a cyclic nonlinear elastic framework allows for the generation of hysteresis (and energy dissipation). This model is the nonlocal version of IC MAGE M02., {"references":["Been, K. and Jefferies, M.G. (1985) A state parameter for sands. Geotechnique, 35(2), 99-112. https://doi.org/10.1680/geot.1985.35.2.99","Taborda, D.M.G., Potts, D.M. and Zdravković, L. (2016). On the assessment of energy dissipated through hysteresis in finite element analysis. Computers and Geotechnics, 71, 180–194. https://doi.org/10.1016/j.compgeo.2015.09.001","Taborda, D.M.G., Potts, D.M., Zdravković, L. and Pedro, A.M.G. (2018) Incorporating the state parameter into a simple constitutive model for sand. Numerical Methods in Geotechnical Engineering IX. https://doi.org/10.1201/9780429446931","Taborda, D.M.G and Zdravković, L. (2012). Application of a Hill-Climbing technique to the formulation of a new cyclic nonlinear elastic constitutive model. Computers and Geotechnics, 43, 80-91. https://doi.org/10.1016/j.compgeo.2012.02.001"]}

IC MAGE M13 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework in which a stress-dependent elastic response is combined with a Mohr-Coulomb failure criterion. Both the stiffness parameters and the strength parameters are determined following cross-correlated random distributions (either normal or log-normal).

IC MAGE M10 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework in which a stress-dependent elastic response is combined with a Mohr-Coulomb failure criterion. Both the stiffness parameters and the strength parameters are determined following independent random distributions.

IC MAGE M07 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which provides a simple way of modelling the stiffness increase observed in concrete during concrete, following the expression by the CEB-FIP (1990)., {"references":["Taborda, DMG, Kontoe, S, Tsiampousi, A (2021, July 23) \"IC MAGE UMIP – universal model interface for PLAXIS (Version 2.1)\". Zenodo. doi: 10.5281/zenodo.5123555"]}

IC MAGE M06 is a user-defined model for PLAXIS built using the IC MAGE UMIP framework which combines a Modified Cam-clay (MCC) model on the wet side of Critical State and a non-linear Hvorslev (HV) surface on the dry side with the IC.G3S isotropic small strain shear stiffness model. It allows for the generation of hysteresis (and energy dissipation) by adopting a cyclic nonlinear elastic framework. The bulk stiffness is defined by the elastic behaviour within MCC.

Seawalls are constructed by covering and protecting the sloping seashore ground with concrete plates or blocks. Their purpose is to sustain high waves induced by strong winds and prevent ground erosion, but they often collapse, mobilising different modes of failure, including that of the ground. Nevertheless, limited research has been conducted on ground failure caused by high waves. In this study, a series of novel centrifuge model tests was first conducted to investigate the failure mechanisms of seawalls due to wave propagation, focusing on the failure of the ground. Finite-element analyses were subsequently conducted to explore the failures observed in the model tests and to provide further insight as to the state of the ground leading to failure. Two failure modes were demonstrated to prevail: floating of the covering panel and sliding failure of the ground. In addition, of the possible causes of failure, the following three were identified in the current study: increased unit weight and reduced suction from wetting; enhanced seepage force under the panel and around the toe block during backwash; water pressure on the back of the panel and the landward side of the toe block during backwash.

Cone Penetration Tests (CPTs) can be used to determine in-situ soil properties and represent a practical choice for site investigation offshore, especially for linear infrastructure, such as offshore wind export cables. Information gained from CPTs is key for predicting soil-structure interaction behaviour, for example when predicting the tow forces involved in seabed ploughing, as the CPT provides an analogue to the process. The numerical modelling of CPTs is challenging due to the significant distortion in the soil displaced by the penetrating cone. This means that solving this sort of problem using finite elements, although not impossible, is numerically tiresome in terms of remeshing and mapping of state variables. Therefore, in this paper we adopt the Material Point Method (MPM) to develop a CPT prediction tool in layered soils. This MPM is combined with a novel non-matching mesh frictional boundary to represent the penetrometer. The developed tool will be used to understand the response of layered soils commonly found offshore as a step towards predicting the interaction of ploughs and anchors with the seabed.

The Material Point Method (MPM) is advertised as the method for large deformation analysis of geotechnical problems. However, the method suffers from several instabilities which are widely documented in the literature, such as: material points crossing between elements, different number of points when projecting quantities between the grid and points, etc. A key issue that has received relatively little attention in the literature is the conditioning of the linear system of equations due to the arbitrary nature of the interaction between the physical body (represented by material points) and the background grid (used to solve the governing equations). This arbitrary interaction can cause significant issues when solving the linear system, making some systems unsolvable or causing them to predict spurious results. This paper presents a cut-FEM (Finite Element Method) inspired ghost-stabilised MPM that removes this issue.

There is considerable interest in the Material Point Method (MPM) in the computational geotechnics community since it can model problems involving large deformations, e.g. landslides, collapses etc. without being too far from the standard finite element method, which can struggle with large deformation problems. The open-source code AMPLE developed at Durham University in recent years is a compact set of MATLAB functions that “address the severe learning curve for researchers wishing to understand, and start using, the MPM”. It is well known that MATLAB can be very slow hence limiting its utility for major studies of large problems, so here we introduce an MPM code with the same aims as AMPLE but written in the relatively new language Julia, specifically for fast runtimes. We highlight areas where MATLAB code constructs are inefficient if just transferred to Julia and show that to unlock large speed gains with Julia, one needs to code in a different way and we demonstrate this on a geotechnical problem. While this paper is concerned with the MPM, the advice regarding coding using Julia is transferable to other computational geotechnics methods and tools.